Motor train unit grinding sub-material and preparation method thereof

Abstract

In order to solve the problems that an existing grinding sub-material is insufficient in material performance and high in maintenance cost, the grinding sub-material comprises a steel backing and a grinding body, and the grinding body is prepared from, by mass, 20-30% of reduced iron powder, 20-30% of iron powder, 5-10% of iron powder, 5-10% of iron powder, 5-10% of silicon powder and 5-10% of silicon powder. 20-30% of calcium sulfate whisker; 0.5 to 1.5 percent of carbon aluminum titanium ternary ceramic (Ti3AlC2); 1-4% of zircon sand; 10-20% of artificial graphite; 1-3% of antimony sulfide; and the balance of modified phenolic resin. The preparation method comprises the following steps: weighing the raw materials, kneading and mixing, re-granulating, drying, forming, drying after demolding, and carrying out surface plastic spraying treatment. The wear resistance and high-temperature stability can be improved, and the service life is prolonged; wheel treads are protected, and noise and maintenance cost are reduced; meanwhile, the system is suitable for severe weather such as rain and snow and ensures safe operation of the motor train unit. The invention relates to the technical field of rail transit.

Description

Technical Field

[0001] The present invention relates to the technical field of rail transportation, and in particular to an EMU train grinding sub-material and a preparation method thereof. Background Art

[0002] With the increase in EMU train speed and the application of high-power disc brakes, the effective adhesion coefficient between the wheel and the rail and the roundness of the wheel are becoming increasingly important. If the adhesion coefficient is insufficient, the wheel and the rail will slip, causing serious damage to the tread. If the roundness of the wheel changes after running for a period of time, the EMU will vibrate when running at high speed. In order to improve the safety, stability and comfort of EMU trains, EMU trains are generally equipped with grinding wheels. The grinding wheel is an important component of the wheel tread cleaning device of high-speed rail and urban rail trains. It has two main functions: one is to remove rust, grease and various impurities that damage the wheel tread during the operation of the EMU to ensure that the wheel tread is in good condition; the other is to repair the wheel roundness while removing dirt to ensure smooth operation of the train. The higher the speed of the EMU train, the higher the performance requirements for the grinding wheel.

[0003] The existing technology has the following defects and deficiencies:

[0004] Inadequate material performance: Existing grinding sub-materials are prone to uneven wear and poor thermal stability under high-speed and heavy-load conditions, resulting in damage to wheels and loud noise, affecting the cleaning and repair effects and the comfort and safety of EMU operation.

[0005] High maintenance cost: The grinding disc wears out quickly and needs to be replaced frequently, which results in high maintenance cost. Summary of the Invention

[0006] The present invention aims to solve the problems of insufficient material performance and high maintenance cost of existing grinding wheels, and further proposes a grinding wheel material for an EMU train and a preparation method thereof.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] The invention discloses an abrasive material for a train set, comprising a steel back and an abrasive body. The abrasive body comprises, by mass percentage, 20-30% reduced iron powder; 20-30% calcium sulfate whiskers; 0.5-1.5% carbon-aluminum-titanium ternary ceramic (Ti3AlC2); 1-4% zircon sand; 10-20% artificial graphite; 1-3% antimony sulfide; and the balance being modified phenolic resin.

[0009] Furthermore, the modified phenolic resin is a rubber-modified phenolic resin, which has a higher decomposition temperature than unmodified phenolic resin and significantly improves mechanical properties and high-temperature stability.

[0010] Furthermore, the carbon-aluminum-titanium ternary ceramic (Ti3AlC2) has a hexagonal layered crystal structure.

[0011] Furthermore, the length of the calcium sulfate whiskers is greater than 100 microns.

[0012] Furthermore, the particle size of the reduced iron powder is -80 mesh.

[0013] Furthermore, the artificial graphite is obtained by high-temperature graphitization of petroleum coke.

[0014] The method for preparing a grinding sub-material for a train of a motor vehicle of the present invention comprises the following steps:

[0015] Step 1. Weigh the raw materials according to the mass fraction of each raw material in the grinding body, wherein: reduced iron powder 20-30%; calcium sulfate whiskers 20-30%; carbon aluminum titanium ternary ceramic (Ti3AlC2) 0.5-1.5%; zircon sand 1-4%; artificial graphite 10-20%; antimony sulfide 1-3%; modified phenolic resin is the balance.

[0016] Step 2: The material weighed in step 1 is loaded into a kneader and kneaded under vacuum and pressure conditions to achieve full modification and mixing of the material;

[0017] Step 3, re-granulating the material after kneading in step 2;

[0018] Step 4: drying the granulated material under vacuum conditions;

[0019] Step 5: Clean the dirt on the steel back and dry it; spray high-temperature glue on the contact surface between the steel back and the grinding body; and place the glue-sprayed steel back into the grinding mold;

[0020] Step 6: Weigh the dried material according to the required weight of the grinding body and put it into the mold for pressure forming;

[0021] Step 7: The demoulded grinding pieces are placed in a drying oven for post-processing;

[0022] Step 8: spray-coat the surface of the grinding sub-piece.

[0023] Furthermore, in step 2, kneading is performed at 150-180° C. under vacuum and pressure conditions for 20-40 minutes.

[0024] Furthermore, in step 4, the drying temperature is 50-80° C., and the drying time is 1-3 hours.

[0025] Furthermore, in step 6, the mold is heated to 150-180°C and pressure forming is started at a pressure of 5-20 MPa for 30-60 minutes, with exhaust every 15-25 seconds.

[0026] Furthermore, in step 7, the temperature control accuracy of the drying furnace is ±2°C, and the post-treatment is maintained at a constant temperature of 50-60°C and 100-120°C for 0.5 hours each, and at 150-180°C for 4-10 hours.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention uses rubber-modified phenolic resin as a bonding component to significantly increase the decomposition temperature and prolong the aging time, allowing the grinding wheel to maintain stable performance under high-speed and high-temperature conditions. The use of carbon-aluminum-titanium ternary ceramic (Ti3AlC2) and zircon sand as the friction phase improves the cleaning and repair capabilities of the grinding body while reducing its own wear. The addition of calcium sulfate whiskers and reduced iron powder makes the grinding body have higher strength and prevents it from breaking or falling off.

[0029] 2. In the present invention, the chain-like molecular structure of antimony sulfide can reduce friction noise, and at the same time, combined with the lubricating effect of graphite, it can reduce vibration and improve the balance and comfort of train operation;

[0030] 3. In adverse weather conditions such as rain, snow, and ice, the grinding wheel can effectively remove rust, grease, and impurities from the wheel tread, maintaining the optimal adhesion coefficient between the wheel and the track to prevent slipping;

[0031] 4. The present invention adopts economical raw materials such as calcium sulfate whiskers and artificial graphite to reduce production costs while ensuring performance. DETAILED DESCRIPTION

[0032] Specific embodiment 1: The abrasive material for an EMU train described in this embodiment includes a steel back and an abrasive body. The steel back adopts the national standard grade Q235 and is not the main content of the present invention. The main content of the present invention is the material design of the abrasive body and the preparation method of the abrasive. The main function of the abrasive body is cleaning and repairing. A high-performance abrasive must have good wear resistance, sufficient strength, and a good adhesion coefficient between the wheel and the rail; it must have a good repair function for the wheel without damaging the wheel tread; it must have high-temperature performance stability and ensure that the grinding chips and the wheel do not adhere to each other during the cleaning and repair process. These properties of the abrasive are particularly important in rainy, snowy, and icy weather.

[0033] The abrasive material is primarily composed of bonding components, friction components, reinforcement components, lubrication components, and filler components. Different materials constitute different components, and different components perform different functions. Some components can be composed of multiple materials, and a certain material can also have the functions of different components. The present invention uses modified phenolic resin and iron powder as the matrix materials, and calcium sulfate whiskers, carbon-aluminum-titanium ternary ceramic (Ti3AlC2), zircon sand, graphite, and antimony sulfide as additives. High-performance EMU abrasives are prepared through key processes such as kneading, mixing, and mold forming.

[0034] In the present invention, the grinding body comprises, by mass percentage, 20-30% of reduced iron powder; 20-30% of calcium sulfate whiskers; 0.5-1.5% of carbon-aluminum-titanium ternary ceramics (Ti3AlC2); 1-4% of zircon sand; 10-20% of artificial graphite; 1-3% of antimony sulfide; and the balance is modified phenolic resin.

[0035] The modified phenolic resin is modified with rubber. The modified phenolic resin significantly increases the decomposition temperature, prolongs the aging time, and greatly improves the mechanical properties and high-temperature performance, ensuring that the grinding wheel can work stably under different working conditions. In the present invention, the modified phenolic resin is the resin adhesive component, with a content of 20-30%.

[0036] Reduced iron powder has a sponge-like appearance. Due to its micropores, it tightly bonds with the adhesive component after kneading and is not easily detached. Therefore, the addition of reduced iron powder to the grinding medium imparts greater strength. Furthermore, due to its low hardness, low price, and excellent wear resistance, its addition to the grinding medium can protect the wheel tread. In the present invention, the reduced iron powder serves the dual functions of a friction component and a filler component, with a particle size of -80 mesh and a content of 20-30%.

[0037] Calcium sulfate whiskers are non-toxic, flame-retardant, corrosion-resistant, and highly compatible with polymers. They offer exceptional strength, low hardness, high-temperature performance stability, and dimensional stability. They are also low-density and inexpensive, serving as both a friction component, a reinforcement component, and a filler component. The addition of calcium sulfate whiskers significantly improves the mechanical properties of the abrasive, protects wheels from damage, and reduces weight and costs. The present invention utilizes calcium sulfate whiskers with a length of 100 microns or greater, at a mass percentage of 20-30%.

[0038] Carbon-aluminum-titanium ternary ceramics (Ti3AlC2) possess the dual properties of ceramics and metals. Their hardness is higher than that of metals, but significantly lower than that of ceramics. They possess high strength and excellent wear resistance. Because their crystals have a hexagonal layered structure, they also have a certain friction-reducing function. While the grinding wheel is working, it can effectively clean the tread and repair the wheel. Because of its low hardness, it can also protect the wheel. In the present invention, carbon-aluminum-titanium ternary ceramics (Ti3AlC2) are primarily used as a friction component. Due to their excellent material properties, their content only needs to be 0.5-1.5%.

[0039] Zircon sand is a natural silicate mineral, mainly composed of zircon, with high hardness, moderate density, stable molecular structure, good wear resistance, stable high temperature performance, and good cleaning and repairing functions when the grinding wheel is working. In the present invention, it is a friction component and its content is 1-4%.

[0040] Artificial graphite is a high-performance material produced by high-temperature graphitization of organic materials such as petroleum coke. Its molecular structure is a complex polycrystalline arrangement, resulting in a higher hardness than natural graphite, excellent wear resistance, and stable high-temperature performance. During operation, it prevents grinding debris from adhering to the tread, ensuring the adhesion coefficient between the wheel and the rail. Its low price also reduces costs. In the present invention, artificial graphite is primarily used as a lubricating component, while also serving as a filler component, with a content of 10-20%.

[0041] Antimony sulfide has a chain-like molecular structure. Due to the weak molecular forces between the chains, its use is similar to that of layered materials, resulting in excellent friction-reducing properties. It is widely used in friction materials. Abrasives containing antimony sulfide can significantly reduce friction noise during operation, slow the high-temperature decomposition rate of phenolic resin, and improve the performance stability and service life of the abrasives. In the present invention, antimony sulfide primarily serves as a lubricating component, while also serving as a reinforcing component. Its content is 1-3%.

[0042] Specific embodiment 2: A method for preparing a grinding material for an EMU train described in this embodiment includes the following steps:

[0043] Step 1. Weigh the seven materials mentioned above on an electronic balance according to the material formula of the present invention, including: 20-30% reduced iron powder; 20-30% calcium sulfate whiskers; 0.5-1.5% carbon aluminum titanium ternary ceramic (Ti3AlC2); 1-4% zircon sand; 10-20% artificial graphite; 1-3% antimony sulfide; and modified phenolic resin as the balance; the accuracy of the electronic balance shall not be less than one thousandth of the weight of the weighed materials;

[0044] Step 2. Load the weighed materials into a kneader and knead them under vacuum and pressure at 150-180°C for 20-40 minutes to achieve full modification and mixing of the materials.

[0045] Step 3. Re-granulate the kneaded material into granules with a diameter of 2-6 mm and a length of 4-8 mm;

[0046] Step 4. Dry the granulated material under vacuum conditions at a temperature of 50-80°C for 1-3 hours;

[0047] Step 5. Clean the dirt on the steel back and dry it;

[0048] Step 6. Spray high temperature glue on the contact surface between the steel back and the grinding body;

[0049] Step 7. Place the glued steel back into the grinding mold;

[0050] Step 8. Weigh the dried material on an electronic balance according to the required weight of the grinding body. The accuracy of the electronic balance should not be less than one thousandth of the weight of the material.

[0051] Step 9. Heat the mold to 150-180°C and start pressurizing at 5-20 MPa for 30-60 minutes, exhausting every 15-25 seconds.

[0052] Step 10. Remove the formed grinding wheel from the mold;

[0053] Step 11. Place the ground grains in a drying oven for post-processing. The temperature of the drying oven is controlled within an accuracy of ±2°C. The post-processing is carried out at 50-60°C and 100-120°C for 0.5 hours each, and then at 150-180°C for 4-10 hours.

[0054] Step 12: spray-coat the surface of the grinding sub-body.

[0055] Example (taking 100 kilograms as an example):

[0056] Step 1. According to the material formula of the present invention, seven materials are weighed on an electronic balance, including: 30 kg of modified phenolic resin (30%); 25 kg of reduced iron powder (25%); 25 kg of calcium sulfate whiskers (25%); 1 kg of carbon-aluminum-titanium ternary ceramic (Ti3AlC2); 2 kg of zircon sand; 15 kg of artificial graphite; and 2 kg of antimony sulfide. For materials over 10 kg, an electronic balance with a precision of 1 gram is used, and for materials under 10 kg, an electronic balance with a precision of 0.5 gram is used.

[0057] Step 2. Load the weighed material into a kneader and knead at 170°C under vacuum and pressure for 30 minutes;

[0058] Step 3. Re-granulate the kneaded material into granules with a diameter of 4 mm and a length of 6 mm;

[0059] Step 4. Dry the granulated material under vacuum conditions at a temperature of 70°C for 2 hours;

[0060] Step 5. Clean the dirt on the steel back and dry it at 120℃ for 2 hours;

[0061] Step 6. Spray high-temperature glue on the contact surface between the steel back and the grinding body. The thickness of the glue is 0.4mm.

[0062] Step 7. Place the glued steel back into the grinding mold;

[0063] Step 8. Weigh 1800 g of the dried material on an electronic balance with an accuracy of 0.5 g and place it into a mold;

[0064] Step 9. Heat the mold to 165°C and start pressurizing at 10 MPa for 40 minutes, venting every 20 seconds.

[0065] Step 10. Remove the formed grinding wheel from the mold;

[0066] Step 11. Place the ground grains in a drying oven for post-processing. The temperature of the drying oven is controlled within an accuracy of ±2°C. The post-processing temperature is maintained at 60°C and 110°C for 0.5 hours each, and at 165°C for 6 hours.

[0067] Step 12: Spray-coat the surface of the grinding wheel with a thickness of 0.1 mm.

[0068] The grinding wheel produced by the above method has excellent comprehensive performance, which not only increases the service life but also plays a good protective role on the wheel tread.

[0069] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A grinding material for EMU trains, comprising a steel back and a grinding body, characterized in that: The grinding body, calculated by mass percentage, includes: Reduced iron powder 20-30%; calcium sulfate whisker 20-30%; carbon aluminum titanium ternary ceramic 0.5-1.5%; zircon sand 1-4%; artificial graphite 10-20%; antimony sulfide 1-3%; modified phenolic resin is the balance.

2. The grinding material for EMU train according to claim 1, characterized in that: The modified phenolic resin is a rubber-modified phenolic resin.

3. The abrasive material for EMU train according to claim 1, characterized in that: The carbon-aluminum-titanium ternary ceramic has a hexagonal layered crystal structure.

4. The abrasive material for EMU train according to claim 1, characterized in that: The length of the calcium sulfate whiskers is greater than 100 microns.

5. The abrasive material for EMU train according to claim 1, characterized in that: The particle size of the reduced iron powder is -80 mesh.

6. The method for preparing abrasive material for a train set according to any one of claims 1 to 5, characterized in that: The steps include: Step 1, weighing raw materials according to the mass fraction of each raw material in the grinding body, including: 20-30% reduced iron powder; 20-30% calcium sulfate whiskers; 0.5-1.5% carbon aluminum titanium ternary ceramic (Ti3AlC2); 1-4% zircon sand; 10-20% artificial graphite; 1-3% antimony sulfide; and the balance modified phenolic resin; Step 2: The material weighed in step 1 is loaded into a kneader and kneaded under vacuum and pressure conditions to achieve full modification and mixing of the material; Step 3, re-granulating the material after kneading in step 2; Step 4: drying the granulated material under vacuum conditions; Step 5: Clean the dirt on the steel back and dry it; spray high-temperature glue on the contact surface between the steel back and the grinding body; and place the glue-sprayed steel back into the grinding mold; Step 6: Weigh the dried material according to the required weight of the grinding body and put it into the mold for pressure forming; Step 7: The demoulded grinding pieces are placed in a drying oven for post-processing; Step 8: spray-coat the surface of the grinding sub-piece.

7. The method for preparing abrasive materials for EMU trains according to claim 6, characterized in that: In the step 2, kneading is performed at 150-180° C. for 20-40 minutes under vacuum and pressure conditions.

8. The method for preparing abrasive materials for EMU trains according to claim 6, characterized in that: In step 4, the drying temperature is 50-80° C., and the drying time is 1-3 hours.

9. The method for preparing abrasive materials for EMU trains according to claim 6, characterized in that: In step 6, the mold is heated to 150-180° C. and pressure forming is started at a pressure of 5-20 MPa for 30-60 minutes, with exhaust every 15-25 seconds.

10. The method for preparing abrasive materials for EMU trains according to claim 6, characterized in that: In step 7, the temperature control accuracy of the drying furnace is ±2° C., and the post-treatment is carried out at constant temperatures of 50-60° C. and 100-120° C. for 0.5 hours each, and at 150-180° C. for 4-10 hours.